Your eyelids are controlled by several muscles, primarily the orbicularis oculi and the levator palpebrae superioris. The orbicularis oculi is a circular muscle that surrounds the eye and is responsible for closing the eyelids. It has three parts: the orbital portion, palpebral portion, and lacrimal portion. The orbital portion primarily facilitates the voluntary, forceful closure of the eyelids. The palpebral portion helps with gentle eyelid closure, while the lacrimal portion helps with tearing.
The levator palpebrae superioris is a muscle that lifts the upper eyelid. This muscle is controlled by the oculomotor nerve (CN III). When the levator palpebrae superioris contracts, the upper eyelid opens.
In addition to these muscles, the facial nerve (CN VII) also plays a role in eyelid movement. The facial nerve controls the muscles that are responsible for facial expressions, including blinking and squinting.
The eyelids are also supplied by three cranial nerves (III, V, VII) and sympathetic nerve fibers.
These muscles and nerves work together to allow you to blink, open and close your eyes, and protect your eyes from foreign objects and bright light.
